Recently, an imaging sensor such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal-Oxide Semiconductor), and a signal processing circuit are increasingly improved in terms of integration density and come to be available inexpensively. Accordingly, a digital still camera and a digital video camera (hereinafter referred to as a “digital camera”), which are capable of converting an optical image of an object into an electrical image signal and outputting the signal, are rapidly growing popular.
With regard to a shooting attitude of a digital camera, in the case where a horizontally long object such as a landscape is to be shot, a photographer holds the digital camera so as to be in a horizontal attitude. In the case where a vertically long object such as a person or a building is to be shot, the object is shot while the digital camera is being held in a vertical attitude.
Note that an attitude of the digital camera, in the case where the direction of a stroke of a shutter button is in parallel with the gravity direction, is referred to as a horizontal shooting attitude. On the other hand, an attitude of the digital camera, in the case where the direction of the stroke of the shutter button is orthogonal to the gravity direction, is referred to as a vertical shooting attitude.
Further, images, which are shot in the respective attitudes as above described, are referred to as a horizontally shot image and a vertically shot image, respectively. In the case where images shot in these two shooting attitudes are to be reproduced and displayed, an attitude detection means is provided to the imaging device so as to match an orientation at the time of shooting and that at the time of reproduction. At the time of shooting, attitude information of the imaging device is written into a shot image, and when the shot image is displayed, the attitude information is read concurrently with the shot image, whereby the image is displayed such that an orientation thereof corresponds to the orientation at the time of shooting.
When the digital camera is in a downward attitude, the digital camera cannot determine whether it is in the horizontal shooting attitude or in the vertical shooting attitude. Therefore, a system is suggested in which, when the digital camera is detected to be in the downward attitude, a photographer inputs either the horizontal shooting attitude or the vertical shooting attitude into the digital camera, whereby a shot image is displayed such that the orientation thereof corresponds to the orientation at the time of shooting (Patent Document 1).    Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-88439